The invention relates to a method of fabricating a woven, inflatable webbing, more particularly an automotive seat belt webbing.
Known from German Patent 20 08 048 (Rutzki) is a webbing configured tubular and comprising a portionally stitched burst fold designed to burst open due to the tensional forces exerted by the belt in a collision whilst activating opening of a valve connected thereto to inflate the tubular belt portionally, as a result of which the belt located as a flat tube prior to the accident, the width of which corresponds to half the circumference of the inflated belt, is explodingly inflated portionally. It thus represents an xe2x80x9cimpact cushionxe2x80x9d of advantage to a certain extent as compared to the straight-forward belt. However, adequate protection of the vehicle occupant fails to be satisfactorily assured due to the insignificant extent of the portionally inflated tubular belt. Increasing the circumference of the belt tube cited likewise in the same document with an inflatable cushion, arranged portionally about the belt also has its disadvantages since the corresponding cushion is not necessarily correctly located in an emergency situation and thus actually fails to be available for its intended purpose.
Known from the international patent application PCT/US95/10695 (Simula) is a inflatable, tubular restraint system. The seat belt system evident therefrom consists of a lap belt and a shoulder belt, the lap belt consisting portionally of an inflated balloon which during inflation is shortened in length to thus have a belt tensioning function in addition to its impact cushioning function. Although in this arrangement the abdominal zone of the vehicle occupant is particularly protected, no protection is given to the shoulder and head zone, however, except for an additional restraint of the shoulders by the tensioned belt.
The object of the invention is to provide a belt or webbing as well as a method of fabricating same having practically no limitations, i.e. in assuring optimum impact protection irrespective of the actual location in an accident situation and permitting cost-effective and reliable fabrication of the webbing respectively.
This object is achieved by a method as it reads from claim 1 and/or a method as it reads from claim 2 and a webbing as set forth in claim 5.
The method in accordance with the invention for fabricating a webbing comprises (in short) the following steps, weaving a two-ply (upper or first ply, lower or second ply) three or more part (at least one left outer part, middle part, at least one right outer pan) fabric, concertina folding and placement of more than two outer parts, form each outermost outer part to each innermost outer part until the no more than two outer parts are located on the outer parts adjoining note middle part, folding the one outer part adjoining the middle part along the one crease onto an outer surface of the middle part facing away from the second ply, folding the other outer part along the other crease onto the other outer surface of the middle part facing away from the firs ply so thatxe2x80x94as viewed in the warp directionxe2x80x94the configuration of a collapsed concertina materializes and tucking the middle part xe2x80x9cto the leftxe2x80x9d so that the one and other surface of the middle part formally facing away from each other now face each other and sandwich the folded outer parts.
With a webbing fabricated in this way any webbing/air bag configuration is optionally achievable to advantage. Depending on the selected number of outer parts an air bag volume achievable by the air bag belt being inflated as prompted by the collision materializes differing in size, thus permitting adaptation to all differences in vehicle type, seating configuration, occupant stature, body weight to be cushioned, etc. Another advantage is that by additionally nip seaming the outer parts individually from the edgesxe2x80x94outermost in the woven conditionxe2x80x94inwards to the middle part a belt bag volume is attainable which is uneven in the longitudinal direction of the webbing (FIGS. 6 to 8 and 10). As a result of this it is now possible to save having to provide the side air bag usually accommodated in the door cladding and the head bag usually accommodated in the roof ledge above the doors. The vehicle occupant is safeguarded by a sole air bag integrated in the seat belt, i.e. by a belt bag in lap, flank, chest and head zone and protected from injury by impacting vehicle parts, irrespective of his posture, i.e. whether relaxed, slumped or sitting upright. One particular advantage of the method in accordance with the invention and thus of the webbing fabricated thereby is in it saving several expensive air bag systems (at least one door air bag and 1 side/head air bag per vehicle occupant). Nip seaming as mentioned above is not restricted to actual stitching, i.e. seaming, this instead intended to mean all measures undertaken suitable for individually locally joining the top with the bottom fabric ply such as weaving, bonding, welding and the like. It is particularly of advantage and cost-saving to fabricate the nip seam(s) by selectively weaving the top to the bottom fabric ply on a Jacquard weaving machine.
The method in accordance with the invention for fabricating a webbing comprises (in short) the following steps: weaving a two-ply (upper ply, lower ply) three-part (left outer part, middle part, right outer pant) fabric, folding the one outer part along a crease onto the surface of the middle part, folding the other outer part along the other crease onto the other surface of the middle part so thatxe2x80x94as viewed in the warp directionxe2x80x94the configuration of a collapsed Z materializes and tucking the middle part xe2x80x9cto the leftxe2x80x9d so that the one and other surface of the middle pant formerly facing away from each other now face each other and sandwich the folded outer parts.
Weaving may be implemented on a Jacquard wide web weaving machine or a needle web weaving machine. Folding the outer parts is done on simple means suitable for this purpose which are not described further. Tucking the middle part xe2x80x9cto the leftxe2x80x9d is done by introducing a rod or the like tipped with a gripper into a matched length of webbing between the two middle part plies until the gripper reappears at the other open end of the webbing and clamps in the gripper the middle parts folded inwards together with the outer parts folded thereon and then withdrawing the rod together with the gripper contrary to the direction inserted from the interior of the middle part with a suitable counterhold. Once the rod with the gripper is fully withdrawn a fully xe2x80x9cleft-handxe2x80x9d tucked webbing is available in which the outer parts are sandwiched between fabric plies of the middle part. The method in accordance with the invention is thus an advantage because it is so simple and produces smooth webbings.
The weft thread of the webbing in accordance with the invention may be a sole multifil or a multifil with a monofil. Employing monofil as the weft thread results in a stiffer, more elastic webbing. Logos and the like may be, of course, included in the weave of the webbing in accordance with the invention by suitable setting the shanks and shank control, there being no limits to that desired by the user in this respect.
One advantageous further embodiment of the method in accordance with the invention reads from claim 2, it being here in particularly that the warp threads in the region of the narrow creases have a dtex roughly half that of the warp threads of the middle part. If, for example, the warp threads of the middle part are dtex 1100, then the warp threads of the narrow creases are dtex 550. This brings the advantage that in the folded condition in which, as viewed in all, the material of the creases is present in four plies, as compared to the double ply of the middle part, a more or less equal thickness of the folded webbing results over the full width since the warp threads in the creases are roughly half as thick as the warp threads in the middle part.
In a further advantageous aspect of the invention the two fabric plies in the middle portion of the middle part are joined to at least two burst threads running substantially in the warp direction.
In another advantageous aspect of the invention the fabric of the webbing is provided with a coating prior to folding. The coating results in a significant reduction in the permeability of the fabric and enables the internal pressure of an inflated webbing to be maintained over a longer period in time. This is particularly decisive when the vehicle is not abruptly halted by a collision, it instead toppling or continuing its travel so that the vehicle occupant needs to be safely restrained in the vehicle seat correspondingly longer.
Advantageous further embodiments and features of the invention read from the sub-claims.